彩色圖像轉(zhuǎn)灰度圖像

彩色（24位）bmp圖像結(jié)構(gòu)：

typedef struct{bitmapFileHeader bfHeader;bitmapInfoHeader biHeader;unsigned char *imgData;
}bmp;

灰度（8位）bmp圖像結(jié)構(gòu)：

typedef struct{bitmapFileHeader bfHeader;bitmapInfoHeader biHeader;rgbQUAD palette[256];unsigned char *imgData;
}bmp;

bmp灰度圖像比彩色圖像多了一個(gè)調(diào)色板，調(diào)色板中每個(gè)元素的類型是一個(gè)RGBQUAD結(jié)構(gòu)，占四個(gè)字節(jié)，其定義如下：

typedef struct{unsigned char rgbBlue;unsigned char rgbGreen;unsigned char rgbRed;unsigned char rgbReserved;}rgbQUAD;

在實(shí)際的bmp圖像中調(diào)色板：

代碼實(shí)現(xiàn)將彩色bmp圖像轉(zhuǎn)化位灰值圖像：

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#pragma pack(1)   //全緊湊模式typedef struct {unsigned char bfType[2];unsigned int bfSize;unsigned short bfReserved1;unsigned short bfReserved2;unsigned int bfOffBits;
}bitmapFileHeader;typedef struct {unsigned int biSize;unsigned int biWidth;unsigned int biHeight;unsigned short biPlanes;unsigned short biBitCount;unsigned int biCompression;unsigned int biSizeImage;unsigned int biXPixPerMeter;unsigned int biYPixPerMeter;unsigned int biClrUsed;unsigned int biClrImportant;
}bitmapInfoHeader;typedef struct{unsigned char rgbBlue;unsigned char rgbGreen;unsigned char rgbRed;unsigned char rgbReserved;}rgbQUAD;typedef struct{bitmapFileHeader bfHeader;bitmapInfoHeader biHeader;rgbQUAD palette[256];unsigned char *imgData;
}bmp;int main(){FILE *fp;if((fp=fopen("d:\Temp\\test.bmp","rb"))==NULL){perror("can not open file!");return -1;}//讀入彩色bmp圖像文件頭，信息頭和圖像數(shù)據(jù)bitmapFileHeader bfHeader;fread(&bfHeader,14,1,fp);bitmapInfoHeader biHeader;fread(&biHeader,40,1,fp);int imSize=biHeader.biSizeImage;int width=biHeader.biWidth;int height=biHeader.biHeight;int bitCount=biHeader.biBitCount;int lineBytes=(width*bitCount+31)/32*4;fseek(fp,bfHeader.bfOffBits,SEEK_SET);unsigned char*imageData=(unsigned char*)malloc(imSize*sizeof(unsigned char));fread(imageData,imSize*sizeof(unsigned char),1,fp);	fclose(fp);bmp b;int i,j,k;memcpy(&(b.bfHeader),&bfHeader,sizeof(bfHeader));memcpy(&(b.biHeader),&biHeader,sizeof(biHeader));b.bfHeader.bfOffBits=1078;  //因新增了調(diào)色板，需調(diào)整圖像數(shù)據(jù)偏移位置b.biHeader.biBitCount=8;  //改變圖像位數(shù)int lineBytes_new=(width*8+31)/32*4; //重新計(jì)算每行數(shù)據(jù)字節(jié)b.biHeader.biSizeImage=lineBytes_new*height; //改變圖像數(shù)據(jù)大小b.bfHeader.bfSize=1078+b.biHeader.biSizeImage; //改變文件數(shù)據(jù)大小b.imgData=(unsigned char*)malloc(sizeof(unsigned char)*b.biHeader.biSizeImage);memset(b.imgData,0,sizeof(unsigned char)*b.biHeader.biSizeImage);for(i=0;i<256;i++){b.palette[i].rgbBlue=i;b.palette[i].rgbGreen=i;b.palette[i].rgbRed=i;}for(i=0;i<height;i++){for(j=0;j<width;j++){//將每一個(gè)像素都按公式y(tǒng)=B*0.299+G*0.587+R*0.114進(jìn)行轉(zhuǎn)化b.imgData[lineBytes_new*i+j]=imageData[lineBytes*i+j*3]*0.299+imageData[lineBytes*i+j*3+1]*0.587+imageData[lineBytes*i+j*3+2]*0.114;}}char savePath[]="D:\Temp\\save_test.bmp";FILE *f=fopen(savePath,"wb");if(f==NULL){perror("can not open file!");return -2;}fwrite(&b.bfHeader,sizeof(bitmapFileHeader),1,f);fwrite(&b.biHeader,sizeof(bitmapInfoHeader),1,f);fwrite(&b.palette,1024,1,f);fwrite(b.imgData,sizeof(unsigned char)*b.biHeader.biSizeImage,1,f);fclose(f);free(imageData);free(b.imgData);return 0;
}

代碼效果：

灰度圖像反色

	int i,j;for(i=0;i<height;i++){for(j=0;j<width;j++){b.imgData[lineBytes*i+j]=255-imageData[lineBytes*i+j];}}

代碼效果：

總結(jié)

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